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(#) Non-trailing primary composable lambda parameter

!!! WARNING: Non-trailing primary composable lambda parameter
   This is a warning.

Id
:   `ComposableLambdaParameterPosition`
Summary
:   Non-trailing primary composable lambda parameter
Note
:   **This issue is disabled by default**; use `--enable ComposableLambdaParameterPosition`
Severity
:   Warning
Category
:   Correctness
Platform
:   Any
Vendor
:   Jetpack Compose
Identifier
:   androidx.compose.runtime
Feedback
:   https://issuetracker.google.com/issues/new?component=612128
Min
:   Lint 8.0 and 8.1
Compiled
:   Lint 8.0 and 8.1
Artifact
:   [androidx.compose.runtime:runtime-android](androidx_compose_runtime_runtime-android.md.html)
Since
:   1.5.0
Affects
:   Kotlin and Java files and test sources
Editing
:   This check runs on the fly in the IDE editor
Implementation
:   [Source Code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/compose/runtime/runtime-lint/src/main/java/androidx/compose/runtime/lint/ComposableLambdaParameterDetector.kt)
Tests
:   [Source Code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/compose/runtime/runtime-lint/src/test/java/androidx/compose/runtime/lint/ComposableLambdaParameterDetectorTest.kt)
Copyright Year
:   2020

Composable functions with only one composable lambda parameter should
place the parameter at the end of the parameter list, so it can be used
as a trailing lambda.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
src/androidx/compose/ui/foo/test.kt:7:Warning: Composable lambda
parameter should be the last parameter so it can be used as a trailing
lambda [ComposableLambdaParameterPosition]
    fun Button(content: @Composable () -&gt; Unit, foo: Int) {
               -------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is the source file referenced above:

`src/androidx/compose/ui/foo/test.kt`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers
package androidx.compose.ui.foo

import androidx.compose.runtime.Composable

@Composable
fun Button(content: @Composable () -> Unit, foo: Int) {

}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/compose/runtime/runtime-lint/src/test/java/androidx/compose/runtime/lint/ComposableLambdaParameterDetectorTest.kt)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `ComposableLambdaParameterDetector.notTrailing`.
To report a problem with this extracted sample, visit
https://issuetracker.google.com/issues/new?component=612128.

(##) Including

!!!
   This is not a built-in check. To include it, add the below dependency
   to your project.

```
// build.gradle.kts
implementation("androidx.compose.runtime:runtime-android:1.8.0-alpha07")

// build.gradle
implementation 'androidx.compose.runtime:runtime-android:1.8.0-alpha07'

// build.gradle.kts with version catalogs:
implementation(libs.runtime.android)

# libs.versions.toml
[versions]
runtime-android = "1.8.0-alpha07"
[libraries]
# For clarity and text wrapping purposes the following declaration is
# shown split up across lines, but in TOML it needs to be on a single
# line (see https://github.com/toml-lang/toml/issues/516) so adjust
# when pasting into libs.versions.toml:
runtime-android = {
    module = "androidx.compose.runtime:runtime-android",
    version.ref = "runtime-android"
}
```

1.8.0-alpha07 is the version this documentation was generated from;
there may be newer versions available.

NOTE: These lint checks are **also** made available separate from the main library.
You can also use `androidx.compose.runtime:runtime-lint:1.8.0-alpha07`.


[Additional details about androidx.compose.runtime:runtime-android](androidx_compose_runtime_runtime-android.md.html).
(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Using a suppression annotation like this on the enclosing
  element:

  ```kt
  // Kotlin
  @Suppress("ComposableLambdaParameterPosition")
  fun method() {
     problematicStatement()
  }
  ```

  or

  ```java
  // Java
  @SuppressWarnings("ComposableLambdaParameterPosition")
  void method() {
     problematicStatement();
  }
  ```

* Using a suppression comment like this on the line above:

  ```kt
  //noinspection ComposableLambdaParameterPosition
  problematicStatement()
  ```

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="ComposableLambdaParameterPosition" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'ComposableLambdaParameterPosition'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore ComposableLambdaParameterPosition ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

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